| impracticable(adjective, wild, unreasonable, useless, absurd) |
| unworkable(adjective, unreasonable, useless, absurd, impractical) |
| infeasible(adjective, wild, unreasonable, useless, absurd) |
| unattainable(adjective, unreasonable, useless, absurd, impractical) |
| impossible(adjective, perfect, wild, unreasonable, useless) |
| impractical(adjective, perfect, wild, unreasonable, useless) |
| unachievable(adjective, unreasonable, useless, absurd, impractical) |
| inoperable(adjective, wild, unreasonable, useless, absurd) |
| unsustainable |
| inaccessible(adjective, out, impossibility) |
| unrealizable(adjective, unreasonable, impossible, out-of-the-way, unapproachable) |
| absurd(adjective, wild, unreasonable, useless, preposterous) |
| insuperable |
| insurmountable |
| unobtainable(adjective, impossible, impossibility) |
| unusable(adjective, wild, unreasonable, useless, absurd) |
| hopeless(adjective, impossibility) |
| implausible(adjective, impossible) |
| improbable(adjective, wild, unreasonable, useless, absurd) |
| inconceivable(adjective, impossible) |